Spectroscopy is generally known. Spectroscopy relies upon that fact that the atoms and molecules of most materials will absorb radiation of a specific wavelength. In spectroscopy, a sample is bombarded with a radiant signal from a radiant source that is swept through a predetermined frequency range. A detector measures the amount of radiation absorbed at each frequency by the sample as the source is swept through the frequency range in order to determine a composition of the sample.
Devices that use cavity ring-down spectroscopy are also generally known. Such devices provide a highly reliable and accurate method of detecting both the presence and levels of a variety of different gaseous materials.
In general, cavity ring-down spectroscopy is based upon the principle that the presence of a predetermined gas within an optical resonator will change the rate of decay of a coherent signal resonating within the optical resonator. The change in the rate of decay may occur either because the gas changes the frequency of resonance or level of absorption of an optical signal resonating within the resonator.
Cavity ring-down spectroscopy devices require precise timing between a coherent energy source that excites the resonator and the measurement of signal decay. In general, signal decay typically occurs within a few microseconds. Accordingly, the deactivation of the coherent source and subsequent signal measurements must be highly coordinated. However, there are a number of factors that can disrupt this process and the results. Accordingly, a need exists for better methods of controlling this process.